What are the benefits and risks of cold therapy after total knee replacement?
Compared to placebo, cold therapy may improve blood loss, pain, knee range of motion and short-term swelling after total knee replacement (TKR). We are less certain of its effect on blood transfusions, knee function, pain relief, length of hospital stay, quality of life or activity level. Though evidence was limited, there was little concern for serious adverse events with cold therapy.
What is osteoarthritis, and how is it treated?
Osteoarthritis is a degenerative disease of the joints, such as the knee. Osteoarthritis of the knee can cause pain, limit function and worsen quality of life. TKR can help this condition in the long term, but the effects of surgery during the recovery period (up to 6 months after surgery) can leave people weakened and impaired. Cold therapy (cryotherapy) involves the application of low temperatures to the skin surrounding an injury or surgical site. This can be done using bags of ice or specialised devices that deliver cooled water to the area.
What did we want to find out?
We wanted to find out if cryotherapy has effects on blood loss, pain and knee function within 48 hours after TKR.
What did we do?
We searched for studies that investigated cryotherapy compared with placebo in people after TKR. We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.
What did we find?
We included 22 trials where people undergoing TKR received any form of cold therapy (with or without other treatments) and were compared with those not receiving any cold therapy. There were a total of 1839 people, aged between 64 and 74 years old. The outcomes of interest were in the acute phase (within 48 hours of surgery), but some studies included up to 12 weeks of follow-up.
Blood loss was 264 mL less with cryotherapy at up to 13 days after surgery.
• People lost 561 mL of blood with cryotherapy.
• People lost 825 mL of blood without cryotherapy.
Pain (lower scores mean less pain)
Pain was better by 1.6 points on a 0- to 10-point scale with cryotherapy at 2 days after surgery.
• People who had cryotherapy rated their pain as 3.2 points.
• People who had no cryotherapy rated their pain as 4.8 points.
11% more people had a blood transfusion with cryotherapy, or 11 more out of 100, at up to 13 days after surgery.
• 79 out of 100 people had a transfusion with cryotherapy.
• 37 out of 100 people had a transfusion without cryotherapy.
Knee range of motion
Flexion (bending of the knee joint) was 8.3 degrees greater with cryotherapy when people left hospital.
• People who had cryotherapy had 71.2 degrees of flexion.
• People who had no cryotherapy had 62.9 degrees of flexion.
Knee function was 13.2 points better on a 0- to 100-point scale with cryotherapy at 2 weeks after surgery.
• People who had cryotherapy had a function score of 88.6.
• People who had no cryotherapy had a function score of 75.4
Total adverse events
0% more people reported adverse events with cryotherapy, or 0 more out of 100, up to 30 days after surgery.
• 2.7 out of 100 people reported adverse events with cryotherapy.
• 2.1 out of 100 people reported adverse events without cryotherapy.
Withdrawals due to adverse events
0% more people withdrew from the study due to adverse events with cryotherapy, or 0 more out of 100, up to 30 days after surgery.
• 0.4 out of 100 people withdrew due to adverse events with cryotherapy.
• 0.2 out of 100 people withdrew due to adverse events without cryotherapy.
What are the limitations of the evidence?
We have little confidence in the evidence showing that cold therapy may slightly improve blood loss, pain and range of motion after surgery. We are uncertain if it lowers the risk of a blood transfusion, improves knee function, increases the risk of adverse events or contributed to withdrawals due to adverse events. Factors that decreased our confidence include flaws in the study design (participants were not assigned to treatments randomly; some participants dropped out of the study; participants could tell what treatment they were receiving), not having enough studies or participants to be certain about the results, and variations between studies in results and methods.
How up to date is the evidence?
The evidence is current to 27 May 2022.
The certainty of evidence was low for blood loss, pain and range of motion, and very low for transfusion rate, function, total adverse events and withdrawals from adverse events. We are uncertain whether cryotherapy improves transfusion rate, function, total adverse events or withdrawals from adverse events. We downgraded evidence for bias, indirectness, imprecision and inconsistency. Hence, the potential benefits of cryotherapy on blood loss, pain and range of motion may be too small to justify its use. More well-designed randomised controlled trials focusing especially on clinically meaningful outcomes, such as blood transfusion, and patient-reported outcomes, such as knee function, quality of life, activity level and participant-reported global assessment of success, are required.
Total knee replacement (TKR) is a common intervention for people with end-stage symptomatic knee osteoarthritis, resulting in significant improvements in pain, function and quality of life within three to six months. It is, however, acutely associated with pain, local oedema and blood loss. Post-operative management may include cryotherapy. This is the application of low temperatures to the skin surrounding the surgical site, through ice or cooled water, often delivered using specialised devices. This is an update of a review published in 2012.
To evaluate the effect of cryotherapy in the acute phase after TKR (within 48 hours after surgery) on blood loss, pain, transfusion rate, range of motion, knee function, adverse events and withdrawals due to adverse events.
We searched CENTRAL, MEDLINE, Embase, six other databases and two trials registers, as well as reference lists, related links and conference proceedings on 27 May 2022.
We included randomised controlled trials or controlled clinical trials comparing cryotherapy with or without other treatments (such as compression, regional nerve block or continuous passive motion) to no treatment, or the other treatment alone, following TKR for osteoarthritis.
Two review authors independently selected studies for inclusion, extracted data and assessed risk of bias and certainty of evidence using GRADE. We discussed any disagreements and consulted another review author to resolve them, if required. Major outcomes were blood loss, pain, transfusion rate, knee range of motion, knee function, total adverse events and withdrawals from adverse events. Minor outcomes were analgesia use, knee swelling, length of stay, quality of life, activity level and participant-reported global assessment of success.
We included 22 trials (20 randomised trials and two controlled clinical trials), with 1839 total participants. The mean ages reflected the TKR population, ranging from 64 to 74 years.
Cryotherapy with compression was compared to no treatment in four studies, and to compression alone in nine studies. Cryotherapy without compression was compared to no treatment in eight studies. One study compared cryotherapy without compression to control with compression alone. We combined all control interventions in the primary analysis.
Certainty of evidence was low for blood loss (downgraded for bias and inconsistency), pain (downgraded twice for bias) and range of motion (downgraded for bias and indirectness). It was very low for transfusion rate (downgraded for bias, inconsistency and imprecision), function (downgraded twice for bias and once for inconsistency), total adverse events (downgraded for bias, indirectness and imprecision) and withdrawals from adverse events (downgraded for bias, indirectness and imprecision). The nature of cryotherapy made blinding difficult and most studies had a high risk of performance and detection bias.
Low-certainty evidence from 12 trials (956 participants) shows that cryotherapy may reduce blood loss at one to 13 days after surgery. Blood loss was 825 mL with no cryotherapy and 561 mL with cryotherapy: mean difference (MD) 264 mL less (95% confidence interval (CI) 7 mL less to 516 mL less).
Low-certainty evidence from six trials (530 participants) shows that cryotherapy may slightly improve pain at 48 hours on a 0- to 10-point visual analogue scale (lower scores indicate less pain). Pain was 4.8 points with no cryotherapy and 3.16 points with cryotherapy: MD 1.6 points lower (95% CI 2.3 lower to 1.0 lower).
We are uncertain whether cryotherapy improves transfusion rate at zero to 13 days after surgery. The transfusion rate was 37% with no cryotherapy and 79% with cryotherapy (risk ratio (RR) 2.13, 95% CI 0.04 to 109.63; 2 trials, 91 participants; very low-certainty evidence).
Low-certainty evidence from three trials (174 participants) indicates cryotherapy may improve range of motion at discharge: it was 62.9 degrees with no cryotherapy and 71.2 degrees with cryotherapy: MD 8.3 degrees greater (95% CI 3.6 degrees more to 13.1 degrees more).
We are uncertain whether cryotherapy improves function two weeks after surgery. Function was 75.4 points on the 0- to 100-point Dutch Western Ontario and McMaster Universities Arthritis Index (WOMAC) scale (lower score indicates worse function) in the control group and 88.6 points with cryotherapy (MD 13.2 points better, 95% CI 0.5 worse to 27.1 improved; 4 trials, 296 participants; very low-certainty evidence).
We are uncertain whether cryotherapy reduces total adverse events: the risk ratio was 1.30 (95% CI 0.53 to 3.20; 16 trials, 1199 participants; very low-certainty evidence). Adverse events included discomfort, local skin reactions, superficial infections, cold-induced injuries and thrombolytic events.
We are uncertain whether cryotherapy reduces withdrawals from adverse events (RR 2.71, 95% CI 0.42 to 17.38; 19 trials, 1347 participants; very low-certainty evidence).
No significant benefit was found for secondary outcomes of analgesia use, length of stay, activity level or quality of life. Evidence from seven studies (403 participants) showed improved mid-patella swelling between two and six days after surgery (MD 7.32 mm less, 95% CI 11.79 to 2.84 lower), though not at six weeks and three months after surgery. The included studies did not assess participant-reported global assessment of success.